The technical difficulties which arise in the laundering of clothes can be classed into two groups. First there are the difficulties which become manifest in a single wash, and second there are those which only become apparent after a plurality of ‘wash-and-wear’ cycles. In the first group are found problems such as wrinkling of the clothes, whereas in the second are found problems of progressive colour loss and mechanical damage.
Our co-pending patent application GB 0030177.0 relates to the use of a lubricant during the laundering process to prevent the visible appearance of local colour loss through a build-up of mechanical damage during repeated laundering. As will be appreciated, the extent to which this damage will occur is significantly Influenced by the wash conditions. For machine-washing conditions can be classed into two broad types. In so-called ‘European’ washing machines the axis of rotation of the machine is generally horizontal and relatively low levels of water (typical liquor to cloth ratios below 10:1) and high temperatures are used (typically at or above 40 Celsius). In so-called ‘US’ washing machines, the axis of the machine is vertical and relatively high levels of water (typically above 15:1) and lower temperatures (typically below 40 Celsius) are used. US washing conditions also include tumble drying to a greater extent and this can lead to more damage from this source. A further important difference between the US and the European laundry markets is that in the US the majority of main-wash products are liquids whereas solid products (powders and tablets) are more commonplace in Europe.
Suitable lubricants disclosed in GB 00301377 include: polyacrylate salts, polyacrylic acids, polyacrylamides, co-polymers of these various acrylic materials, dextrans, poly vinyl pyrrolidones, poly-dimethyl siloxanes, and, lightly oxidised polyethylene wax.
Oily sugar derivatives were first proposed as lubricating oils for aircraft engines. Due to their lubricant properties and indigestibility they have since been exploited as “fat replacers” in foodstuffs. They are also known in fabric softener compositions. Typically these materials are the products obtainable by esterification of a sugar, such as a saccharide (or other cyclic polyol), with a fatty material. These materials are non-toxic and inherently biodegradable and will be referred to herein as sugar polyesters (“SPE's”). As noted above SPE's have been proposed for use in fabric conditioners and/or softeners.
U.S. Pat. No. 5,447,643 (Huls) discloses aqueous fabric softeners comprising nonionic surfactants. Suitable nonionic surfactants include materials with one to four long hydrophobic chains and a glucose or polysaccharide radical.
WO 96/15213 (Henkel) discloses fabric softening agents containing alkyl, alkenyl and/or acyl group containing sugar derivatives, which are solid after esterification, in combination with nonionic and cationic emulsifiers.
WO 98/16538 (Unilever) discloses rinse-added fabric softening compositions comprising liquid or soft solid derivatives of a cyclic polyol or a reduced saccharide which give good softening and retain absorbency of the fabric.
WO 01/46513 (Unilever) relates to fabric treatment compositions which comprise an oily sugar derivative and one or more deposition aids. The benefit obtained by the use of these compositions is to reduce wrinkling of the fabrics and therefore reduce the need for ironing. The deposition aids are selected from cationic surfactants, cationic softeners, cationic polymers and mixtures thereof. Nonionic surfactants (including alcohol ethoxylate with an HLB of from 11 to 16) are optional ingredients. Example 3 of that specification disclose a (phosphate) built, main wash composition with 3% cationic surfactant (CTAB), 18% nonionic surfactant (C11–13, 3–7EO) and 15% sucrose poly erucate.